This invention relates to ABA triblock copolymers wherein the A segments are polyolefin and the B segments are polycarbonate.
Polycarbonate polymers are well known, commercially available materials having a variety of applications. Such carbonate polymers may be prepared by reacting a polyhydroxy compound, such as 2,2-bis(4-hydroxy phenol)-propane, with a carbonate precursor, such as phosgene, in the presence of an acid binding agent. Generally speaking, the polycarbonate resins have excellent physical properties, including tensile and impact strength, heat resistance and dimensional stability, are usable over wide temperature limits and have good creep resistance. However, the polycarbonates are expensive, difficult to process from a melt because of high viscosities at temperatures slightly above the melting point and exhibit severe environmental stress grazing and cracking.
In general, polycarbonates are incompatible with other polymers, particularly polymers derived from ethylenically unsaturated monomers, thereby inhibiting the use of other polymeric materials in order to modify polycarbonate compositions or to use polycarbonates as modifiers for other polymer compositions.